1. Field of the Invention
The present invention relates generally to independent suspensions for automotive vehicles. More particularly, the present invention relates to an independent suspension having a double isolated shock absorber strut assembly.
2. Disclosure Information
In a typical MacPherson or modified MacPherson suspension geometry, such as shown in FIG. 1, a wheel support member 10 rotatably supports the vehicle roadwheel 12. As used herein, "wheel support member" refers to either a knuckle/spindle assembly used to support the steerable wheels of a vehicle or to a spindle assembly supporting the nonsteered wheels of the vehicle. A shock absorber strut assembly 14 is connected to the vehicle body 15 via an elastic or resilient suspension support member 18. In the conventional suspension geometries, the wheel support member 10 is rigidly connected to the lower end of the shock absorber strut assembly 14 at a single location 16. In such a configuration, as the roadwheels travel over a nonsmooth surface, vibrations resulting from contact of the roadwheel with the road surface are transmitted directly from the spindle through the rigid connection with the shock absorber strut assembly to the vehicle body, resulting in undesirable vibration and noise experienced by the vehicle occupants.
Various attempts at isolating the noise and vibration of the roadwheel through the shock absorber have been proposed. Typically, most systems employing a shock absorber strut assembly utilize an elastomeric bushing or mount at the vehicle body to isolate the noise and vibration of the roadwheel. Examples of these solutions are shown in U.S. Pat. Nos. 2,967,066; 4,756,517; 4,877,262; 4,441,593; and Great Britain Patent Nos. 1,397,965; and 2,039,259. Although adequate for minimizing some of the road vibrations, the above embodiments do not completely remove the undesirable noise, vibration and harshness effects transmitted to the vehicle body. The above systems do not isolate the shock absorber strut unit from the wheel support member and, therefore, do not eliminate the roadwheel vibration from the suspension unit. Therefore, there is a need to isolate the shock absorber strut suspension unit from the wheel support member due to the roadwheel to minimize the amount of vibrations passing to the vehicle body.
U.S. Pat. Nos. 4,105,222 and 4,341,396 both disclose independent strut type suspension systems wherein the shock absorber strut assembly is rigidly secured at two locations to the vehicle spindle. The '222 patent does not teach or suggest the use of any resilient means to isolate the vibrations from the roadwheel to the strut assembly at the mounting locations on the vehicle strut, allowing road vibrations to pass through the spindle to the strut. In the '396 patent, the strut is connected to the axle rack by a pair of legs which are articulated to upper and lower extensions of the axle rack. The upper and lower leg extensions are rigidly connected to the strut housing and, therefore, do not isolate the strut from the road vibrations.
The present invention addresses the problem of vibrations passing from the roadwheels through the shock absorber strut assembly to the vehicle body and attempts to isolate the shock absorber strut from the vibrations through the use of a wheel support member having a pair of bushings which isolate the shock absorber from the vehicle spindle. It is an object of the present invention to provide a wheel support member assembly wherein a shock absorber strut assembly is secured resiliently at two locations within the knuckle to isolate the shock absorber strut assembly from the road vibrations.
It is a feature of the present invention that road vibrations of the vehicle roadwheels are not transmitted to the body of the vehicle through the use of a pair of resilient bushings circumferentially surrounding the shock absorber strut assembly.
It is a further feature of the present invention that the resilient bushings allow a limited amount of movement of the wheel support member relative to the shock absorber strut assembly in a direction generally parallel to longitudinal axis of the strut as well as for pivotal movement of the strut assembly around a longitudinal axis of the strut.
These and other objects, features and advantages of the present invention will become apparent from the summary, descriptions, drawings and claims which follow.